MathCastle
Proof WritingMediumInduction

Induction · Medium problem

Induction proves 11⋅2+12⋅3+⋯+1n(n+1)=nn+1\dfrac{1}{1\cdot2} + \dfrac{1}{2\cdot3} + \cdots + \dfrac{1}{n(n + 1)} = \dfrac{n}{n + 1}. In the step, kk+1+1(k+1)(k+2)\dfrac{k}{k + 1} + \dfrac{1}{(k + 1)(k + 2)} must simplify to what?